Intonational phonology models pitch patterns as sequences of discrete tones (H for high, L for low) anchored to prosodic constituents. Unlike tone languages where pitch lexically distinguishes words, intonation expresses pragmatic and grammatical meaning—questions typically rise, statements fall, and focus shifts pitch peaks. Intonational systems are learned and vary across languages.
From suprasegmental phonology, you know that some phonological features — stress, tone, length — operate above the level of individual segments, applying to syllables, words, and larger prosodic units. Intonational phonology extends this analysis to the level of entire utterances. Its central move is to treat intonation not as a continuous, analog melody but as a sequence of discrete, categorical tonal events that can be labeled, predicted, and described systematically.
The basic notation uses two labels: H (high tone) and L (low tone), which combine to represent pitch movements. These tones are anchored to specific prosodic positions within the intonational phrase. The most important position is the nuclear accent — the most prominent pitch event in the utterance, typically placed on the word carrying the heaviest information load. A falling nuclear contour (moving from high to low: H*L) is associated with statements and strong assertions in English: "She LEFT" said with finality. A rising nuclear contour (L*H) is associated with questions and incompleteness: "She LEFT?" with the meaning held open. These are not metaphorical descriptions of emotion — they are categorical phonological contrasts, as systematic as the difference between /p/ and /b/.
The key insight is that intonation is a linguistic system, not mere expression. In tone languages like Mandarin or Yoruba, pitch is lexical — it distinguishes word meaning at the morpheme level. In intonational languages like English, pitch does not change word meaning but encodes pragmatic and grammatical information at the utterance level. The same string of words — "He's leaving" — means something different depending on whether the nuclear tone rises or falls. More subtly, placing the nuclear accent on different words shifts pragmatic focus: "I saw JOHN" (not someone else) versus "I SAW John" (I didn't just hear about it) versus "I saw John YESTERDAY" (not today). These are distinct intonational claims about which information is new or contrastive.
Intonational systems are language-specific and must be learned. What sounds like a "natural" rising question intonation in English is not universal — many languages use falling intonation for questions, or mark questions through grammatical particles rather than pitch at all. A learner of English as a second language must acquire English intonational patterns as genuine linguistic knowledge, not as transparent expression. This cross-linguistic variation is one of the strongest pieces of evidence that intonation is a phonological system governed by rules — not simply a reflection of the speaker's emotional state.